With the remarkable development of a solid light emitting element such as LED in recent years, a lighting device using the solid light emitting element as a light source has been widely used in various types of lighting equipment as a small-sized, light-weight, low power consumption and long-life light source excellent for environmental protection, and such a lighting device has been used also as a vehicle headlight device excellent in visibility in which various types of control are possible as an on-vehicle electronic device.
For example, as a conventional vehicle headlight device, a vehicle headlamp comprising: a low-beam LED light source array; a high-beam LED light source array; a first optical light guide configured to receive low-beam light and high-beam light from these LED light sources to collimate them; and a second optical light guide configured to diffuse the collimated low-beam light and high-beam light as a combination of diffusion patterns, wherein these arrays and optical light guides are mechanically supported in a casing has already been known by the following Patent Document 1.
Also, according to the Patent Document 2, as a vehicle lamp using a laser light source as a light source and capable of adjusting brightness with a simple configuration, a vehicle lamp using a liquid crystal unit is disclosed. Specifically, a non-modulation region capable of transmitting laser light and a modulation region which changes a phase of a polarization component of the laser light by 90 degrees are formed in the liquid crystal unit, and the brightness of the peripheral light is adjusted by adjusting the ranges of the modulation region and the non-modulation region by a liquid crystal driver.
In addition, according to the following Patent Document 3, a LED lighting equipment, in particular, a LED headlight which uses a plurality of LEDs as an active light source and is configured to emit the light from the active light source with a predetermined orientation through a collimation optical unit, a mixing optical unit, a field optical unit and others is disclosed. Also, claim 25, the paragraph [0036] and others particularly describe that an optical element such as a lens or reflector for polarization or reformation may be further disposed as means for making the light emitted from the active light source reach the mixing optical unit with a desired form.